Electrical resonator



Nov. 21, 1950 N. L. HARRIS ET AL ELECTRICAL RESONATOR Filed Jan. 4, 1947 Summer Nmrm an infiarri- Eu & Jwhm WR I de @A Patented Nov. 21, 1950 Walter Byde, Northwood, l lnglandgass ignors tjo M. 0.-Va1ve Company Limited, gaporporation -of Great Britain Application January 4, IMZL SeriaL-No.120,286

' I V In Great Britain Apr i l 2 2 1 94 1 Section 1, Public Law 690, August 8; 1946 Patent expires April 22,--1960 11 Claims.

This invention relates to electric resonators or the type comprising a metallic wa11,--closed except; for one or two apertures and so shapedthat the ifield .within: the wall. can be excited tooscillations, whose frequency depends on theshape and-fsize of the-resonator.

An object of .thednventionis:toprovide an electric-1resonator whichymay be altered ;in shape and dimensions upon application of heat and thereby its natural frequency. changed or adjusted.

:Another: object ofutheinventioniis {to provide amelec-tric resonator :which will rnaintain a constant frequency under varying temperatures tending to alterits naturaltrequency.

A- particular advantage, of the invention is that simple theat responsive elements may be fitted to the resonators iorqadjustment of the efiective resonant; frequency.

Another-advantage of the invention is that resonators constructed. in accordance therewith arethermally stable and self-compensating as to resonant frequency. 7

Other obj ects and advantages {Will-be apparent from the following description of. the invention, defined in particularity in the appended claims and :takenin connection with the accompanying drawing in which:

Figure 1 is anelevationalview in cross section of a resonator having means externaltotthe resonator to adjust itseffective resonance upon application of heat; a I

Figure Z-isan elevational-rviewin cross section pi a modified form incorporatingthe heat (responsiveelement within the body of the resonator;

Figure 3 isapartial top .view taken along line 3-.-3 of Figure 2 Eigurefleis a perspective view of another embodiment of the invention, and

iFigure' is a partial view incross section taken alongline 55 of Figure 4.

Broadly the invention contemplates the construction of an electric resonator of the cavity type in various forms with one or more .flexible orfi deformable parts whichwhen acted upon by a suitably'directed force. will change the dimensions and effectiveiresonance. of theresonator. These partsin accordance.withtheinvention are actuated by a heatresponsive element suchas a bimetallic member or the-parts themselves may be madeof bimetal'and-become distortable upon application of heat.

:;The, thermal distortable part; or membermay serve peither: ofrtwo purposes or both;- of 3717118111.,

Qne is ;to.. main;t,ain-the natural. frequency constant in-spite of :thermal expansion or cont aoe tiqnyin .th'e-rest-ot theapparatus, dueto changes in ambient temperaturepr to the-heating 0f: the resonatorby .the energy-dissipated in, it when it oscillates thenlno heater is required. ".Th-ispurposemay be usefully served whetherthe resonatoris .or is not enclosed in a sealed envelope. The other purpose is to changeldeliberately the natural frequencyvof the resonator; then a heater through which electric current can be passed must be assoc a ed .-Wi h pa t ,orvmembe .Th sec nd unct o s ,imost, use ulwhen .the r on t n e cl s in a s a e enve ope- Fer th e rp se o il stratin th app i a io .o th -invention todcavity t pev esona c a toroid orm was. c nes a epre ta ive ty bein w de used i certain e ec ro i ch d v es- -,w, ;.-b c ea tha -th in e t is app b -es wel to resonat of o h e metr ca -r0 m- -Resona tors of the typeshown are often placed n n e a uate p e hen t e l ormartap an el ct ondi c er e d een the. ezu s.h n shown ioricon rol thei esonan re u cy is p ti ularl sui for uc c ond ti n .31 t sake o sim h ev uate ;-.s a i {not 9 tl n -i e drawinein ew Qfth ct ha flisno esse i s fa as't operat o o theinventionjs concerned.

Re err n to. thedrawi i Fi u a th onator comprises. the toroidal shell 6 which by-its particular configuration encloses a toroidal cavity narrowed in the center between the paralel walls 1-. and 8. A central. aperture 9 ;.is provided for the ,excitation of the resonator. In accordance with the invention there. .proyided a flexible disc-shaped wall member II) which is placed inside the resonator andattached tothe innerwall insuch manner to be in alignment with theparallel walls land 8. An-aperture l,l; int he member 10 isalso aligned v with the aperturettof the resonator so as not to.impede the passageof char edparticles-which may be utilizedfor exciting the re'sonator.

The flexible wall member |0 is in effect amovable-extension of the parallel wall=8 andwhen moved axially with respect-J 0 the resonat or.. wi ll alter the effective space or distance betweenthe walls "land-8. As iswellknown; this.;;space is n v o h e erm n n -fa o eo th re onan frequenc o h r o a eff sub tantia1. mOvement of'the member J0;- a rod 12; enters, the--wa1l 8;through-;a-;suitable aperture J3 and is attached at, oneend to .=the member 1H1 and at the other end to a strip M of heat responsive element which is secured to the resonator by means of a support l5. The strip l4 may be made of a bimetallic material or similar heat responsive element which flexes or deforms upon application of heat. The strip I4 is shaped in such manner that the motion thereof exerts a force on the rod I2 in either direction between the walls I and 8. A motion in the direction toward the wall 1 will decrease the resonant frequency of the resonator whereas a motion of the member ID toward the wall 8 will increase the frequency.

From the above it can be seen that by proper proportioning of the strip M as to heat response, temperature compensation of the resonator may be obtained and a desired resonant frequency maintained while ambient temperature variations occur during operation. On the other hand, the resonant frequency may be deliberately changed at will by providing heating means for the strip [4 such as an electric heating element I 6 connected to wires l1 and I8 through which current may be applied.

In Figures 2 and 3 the modification resides in the flexible member III which in itself forms one of the parallel walls and is a disc with radially oriented slots H3. The segments so produced are composed of bimetallic elements which flex inwardly upon application of heat. The heating element It is placed under the disc ID, that is, under the bottom parallel wall of the toroid.

The modification shown in Figure 4 is particularly suitable where compensation is desired for ambient temperature variations. The resonator is made up of two semi-toroidal halves of conducting plates 6 and 6 peripherally joined together. A series of slots 2| are cut in a radial direction dividing the resonator into a number of segments which possess sufficient resiliency for appreciable elongation in the direction normal to the axis of the resonator. Bimetallic heating strips I 4 are tightly secured for example by welding to the upper and lower halves of the resonator at each segment. partial section of Figure 5. The strips [4 tend to flex inwardly with respect to the resonator in proportion to temperature increase and cause elongation of the segments which counterbalances the normal expansion of the resonator ,1

when the temperature is increased. The reverse condition arises when the temperature decreases.

We claim:

1. A high frequency electric resonator comprising a closed conducting body of toroidal shape enclosing a cavity having dimensions determining a normal resonant frequency, said resonator having in the center spaced parallel walls normal to the axis, a flexible member within said body and having a first portion attached to said resonator adjacent one of said walls and having a second portion movable toward the other of said walls whereby the effective space between said second portion and said other wall and thereby the resonant frequency of said resonator may be altered, and heat responsive means for causing substantial movement of said second portion of said member in accordance with temperature variations.

2. A high frequency electric resonator comprising a closed conducting body of toroidal shape enclosing a cavity having dimensions determining a normal resonant frequency, said resonator having in the center spaced parallel walls normal to the axis, a flexible member within said This is shown in the body and having a first portion attached to said resonator adjacent one of said walls and having a second portion movable toward the other of said walls whereby the effective space between said second portion and said other wall and thereby the resonant frequency of said resonator may be altered, and heat responsive means comprising a strip of bimetallic element afiixed at one end to said resonator and at the other end to said second portion of said member for causing substantial movement of said second portion in accordance with temperature variations.

3. A resonator in accordance with claim 2, further including means for heating said bimetallic element.

4. A high frequency electric resonator comprising a closed conducting body of toroidal shape enclosing a cavity having dimensions determining a normal resonantvfrequency, said resonator having in the center spaced parallel walls normal to the axis, one of said walls being flexible and having a portion movable toward the other of said walls whereby the effective space between said walls and the resonant frequency of said resonator may be altered, and heat responsive means for flexing said wall in accordance with temperature variations.

5. A resonator in accordance with claim 4 wherein said heat responsive means comprises strips of bimetallic elements forming said flexible wall.

6. A resonator in accordance with claim 5, further including means for heating said bimetallic elements.

'7. A high frequency electric resonator comprising a closed conducting body of toroidal shape enclosing a cavity having dimensions determining a normal resonant frequency, said body having in the center a pair of spaced parallel walls normal to the toroidal axis, a flexible member having a peripheral portion attached to said resonator adjacent one of said walls and a central portion disposed between said walls and movable toward the other of said walls whereby the effective space between said central portion and said other wall and thereby the resonant frequency of said resonator may be altered, and heat responsive means for causing substantial movement of said central portion in accordance with temperature variations.

8. A resonator according to claim '7, wherein said heat responsive means comprises a strip of bimetallic element aflixed at one end to said resonator and at the other end to said central portion of said flexible member, and means for heating said element.

9. A high frequency electric resonator compris-v ing a conducting body enclosing a cavity having dimensions determining a normal resonant frequency, said dimensions and resonant frequency being subject to changes due to ambient temperature variations, and means for automatically compensating for said changes to maintain the desired resonant frequency comprising at least one deformable flexible element forming a portion of the wall of said body and adapted upon deforming to alter said dimensions and resonant frequency and means responsive to ambient temperature variations for flexing said flexible wall element in opposition to said changes.

10. A high frequency electric resonator comprising a pair of circular conducting plates peripherally attached to each other and forming a toroidal body enclosing a cavity having dimensions determining a normal resonant frequency,

said dimensions and resonant frequency being subject to changes due to ambient temperature variations, and means for automatically compensating for said changes to maintain the desired resonant frequency comprising a plurality of radially-directed slits formed in said plates dividing said plates into resilient segments, a bimetallic element on each segment, said elements being adapted to flex said segments in response to ambient temperature variations to alter said dimensions and resonant frequency in opposition to said changes.

11. A high frequency electric resonator comprising a conducting body enclosing a cavity having dimensions determining a normal resonant frequency, said dimensions being subject to changes due to ambient temperature variations, said body having in the center a pair of spaced parallel walls, one of said walls being flexible and having a portion movable toward the other of said walls whereby the effective space between said walls and the resonant frequency of said 6 resonator may be altered, and means responsive to ambient temperature variations for flexing said flexible wall in opposition to said changes to automatically compensate for said changes and maintain the desired resonant frequency.

NORMAN LESLIE HARRIS. JOHN WALTER RYDE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

